Fill the bottom of a bowl, dish, pie pan or flowerpot with sand. It's recommended by Native Wildlife Gardening that the item being used is a minimum of 16 inches wide to prevent rapid evaporation.
Add enough water to make the sand moist. Stale beer or a sweet drink can be substituted for water.
Find a spot in full sun and dig a hole for the bowl. Bury the bowl to ground level, making it flush with the dirt.
Put approximately 1 tablespoon of composted manure in the sand. A pinch of salt may also be added; butterflies require additional sodium when mating.
Decorate the puddle with appealing rock, river stone, clam shells, or pine bark. These items, along with twigs, provide perching and sunbathing spots for butterflies.